Kooperative Rotationsisomerie in Polymeren

Pechhold, W.; Blasenbrey, S.

doi:10.1007/bf01525087

Cited by 83 publications

(11 citation statements)

References 3 publications

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“…The class of defects we are concerned with have ' been described by Reneker [30] and more recently by Pechold and Blasenbrey [31]. Keith and Passaglia [32] have considered similar chain defe cts in the form of dislocations and glide in paraffin crystals (see also Predecki and Statton 133]).…”

Section: B Chain Defectsmentioning

confidence: 99%

The intensity as a function of temperature of the low-angle x-ray diffraction maxima of the n-paraffins: Hexatriacontane, tetratetracontane, and tetranonacontane

Sullivan¹,

Weeks²

1970

J. RES. NATL. BUR. STAN. SECT. A.

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The diffrac tion of x-rays by the crystalline n-paraffin s, C36 H ' 4 , C4.H"o, and C". H ",o, was examin e d a t s mall angles -be low se ve n deg re es 2IJ -as a fun c tion of te mp e rature. The Bragg maxima (001) that occ ur at these ang les res ult from a la mell a r re peat di sta nce whic h de pe nd s on th e molec ul a r length. I n ge ne ral the inte nsity of th ese maxim a was found to inc rease with increas ing te mp e rature in a n approximately re versible manne F. All the samp les exp e rie nce d so lid-so lid ph ase tra nsitions in th e te mperature ran ge of observa tion. S eve ral possibl e mecha ni s ms co ns iste nt with th e te mp e rature d e pendence of the inte nsity are considered .

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Section: B Chain Defectsmentioning

confidence: 99%

The intensity as a function of temperature of the low-angle x-ray diffraction maxima of the n-paraffins: Hexatriacontane, tetratetracontane, and tetranonacontane

Sullivan¹,

Weeks²

1970

J. RES. NATL. BUR. STAN. SECT. A.

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“…Here the most important and at the same time simplest one is the so called "kink"-defect formed by two neighboured gauche positions of three successive CH2-groups [12]. Because of the relaxation of the k-selection rule, such defects contribute to some extent to the continuous background absorption.…”

Section: Discussionmentioning

confidence: 99%

Phonon mode coupling and Fano-type antiresonance in polyethylene

Prettl

Frank

1979

Colloid Polymer Sci

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“…A model involving tgtg' t sequences in the PE chain has been suggested by Pechhold 15 ( Figure 10). Rotation of the bonds as indicated necessitates very slight extensions of the chain and results in translation of the jog by 2CH2 groups or one lattice spacing.…”

Section: Chain Conformationmentioning

confidence: 90%

“…Hoffman, et al, 14 have suggested a mechanism proposed specifically for the re-relaxation, which considers the reorientaHon of chains adjacent to the vacancy created by a chain end. Pechhold 15 has suggested that chain conformations containing some gauche bonds in an otherwise trans chain are present in the crystalline regions of PE. He considers the re-relaxation to arise from molecular rearrangement of blocks of tgtg' t sequences.…”

Section: Cryogenic Relaxations In Polymersmentioning

confidence: 99%

A Dislocation Mechanism for Cryogenic Relaxations in Crystalline Polymers

Hiltner

Baer

1972

Polym J

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ABSTRACT:The experimental properties of the 00-relaxation observed in polyethylene, poly(oxymethylene), and poly(ethylene terephthalate) at about 50°K are reviewed. A mechanism is proposed involving the thermally activated redistribution of kinks along a discontinuous dislocation under an applied stress. The activation energy and relaxation intensity are discussed with reference to specific chain conformations in the dislocation. It is suggested that the kinked dislocations arise from external stresses transferred to the crystalline or ordered regions of the polymer possibly via tie molecules. These stresses are greatest in deformed material or material annealed under constraint and accounts for the increase in peak height observed in these specimens.KEY WORDS Cryogenics/ Dislocation/ Polyethylene/ Poly(ethylene terephthalate) / Poly(oxymethylene) / a-Relaxation / Kink / Conformation / Secondary relaxations above 77°K have been observed in many crystalline polymers and the effects of orientation and crystallinity on the relaxation spectrum have been studied by various investigators. Their results are reviewed in the excellent monograph by McCrum, Williams, and Read. 1 The possibility that linear, crystalline polymers might show relaxation processes below 77°K has received less attention. Early investigators reported no relaxation processes below 77°K in polyethylene 2 and poly-(tetrafluoroethylene).3 However, with the use of more sensitive experimental techniques, very low-temperature relaxations have been observed in this laboratory in a number of linear polymers. Moreover these relaxations were found to be very sensitive to the changes in solid-state structure caused by annealing or deformation. Speculation concerning the mechanism responsible for these relaxation processes has been hampered by the lack of experimental information, and only recently has sufficient data become available to warrant a detailed consideration of the underlying mechanism. CRYOGENIC RELAXATIONS IN POLYMERSDynamic mechanical relaxations in polymers 378 in the temperature range 4.2 to 77°K have been reported by a number of authors. Previous workers however have been primarily concerned with polymers containing side groups, and relaxations observed below 100°K were attributed to motions of the pendent group. 2 -7 This assignment has been substantiated for the a-peak in polystyrene (PS) by correlation of mechanical, NMR, and dielectric measurements of polystyrene and a variety of halogenated and

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Kooperative Rotationsisomerie in Polymeren

Cited by 83 publications

References 3 publications

The intensity as a function of temperature of the low-angle x-ray diffraction maxima of the n-paraffins: Hexatriacontane, tetratetracontane, and tetranonacontane

The intensity as a function of temperature of the low-angle x-ray diffraction maxima of the n-paraffins: Hexatriacontane, tetratetracontane, and tetranonacontane

Phonon mode coupling and Fano-type antiresonance in polyethylene

A Dislocation Mechanism for Cryogenic Relaxations in Crystalline Polymers

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